Formation of silicides by rapid thermal annealing over polycrystalline silicon

We have investigated the formation of titanium silicide by rapid thermal annealing in nitrogen and argon ambients over polycrystalline silicon. A sheet resistance of about 3 Ω per square for a 300-A Ti layer was achieved after 900 0C/10-s annealing treatment, which decreased to about 2 Ω per square after 1100 0C/10-s treatment. The silicides were found to be stable during rapid thermal annealing up to 1100 0C/10 s with no or negligible migration of titanium along the grain boundaries in polycrystalline silicon. An external layer (titanium rich, mixture of titanium oxide and nitride) was observed to form during rapid thermal annealing treatment in the nitrogen ambient, but the surface remained clean in the argon ambient